import {
  AdditiveBlending,
  Color,
  LinearFilter,
  MeshBasicMaterial,
  RGBAFormat,
  ShaderMaterial,
  UniformsUtils,
  Vector2,
  Vector3,
  WebGLRenderTarget
} from 'three';
import { Pass } from 'three/examples/jsm/postprocessing/Pass';
import { CopyShader } from 'three/examples/jsm/shaders/CopyShader';
import { LuminosityHighPassShader } from 'three/examples/jsm/shaders/LuminosityHighPassShader';

/**
 * UnrealBloomPass is inspired by the bloom pass of Unreal Engine. It creates a
 * mip map chain of bloom textures and blurs them with different radii. Because
 * of the weighted combination of mips, and because larger blurs are done on
 * higher mips, this effect provides good quality and performance.
 *
 * Reference:
 * - https://docs.unrealengine.com/latest/INT/Engine/Rendering/PostProcessEffects/Bloom/
 */
var UnrealBloomPass = function (resolution, strength, radius, threshold) {

  Pass.call(this);

  this.strength = (strength !== undefined) ? strength : 1;
  this.radius = radius;
  this.threshold = threshold;
  this.resolution = (resolution !== undefined) ? new Vector2(resolution.x, resolution.y) : new Vector2(256, 256);

  // create color only once here, reuse it later inside the render function
  this.clearColor = new Color(0, 0, 0);

  // render targets
  var pars = { minFilter: LinearFilter, magFilter: LinearFilter, format: RGBAFormat };
  this.renderTargetsHorizontal = [];
  this.renderTargetsVertical = [];
  this.nMips = 5;
  var resx = Math.round(this.resolution.x / 2);
  var resy = Math.round(this.resolution.y / 2);

  this.renderTargetBright = new WebGLRenderTarget(resx, resy, pars);
  this.renderTargetBright.texture.name = "UnrealBloomPass.bright";
  this.renderTargetBright.texture.generateMipmaps = false;

  for (var i = 0; i < this.nMips; i++) {

    var renderTargetHorizonal = new WebGLRenderTarget(resx, resy, pars);

    renderTargetHorizonal.texture.name = "UnrealBloomPass.h" + i;
    renderTargetHorizonal.texture.generateMipmaps = false;

    this.renderTargetsHorizontal.push(renderTargetHorizonal);

    var renderTargetVertical = new WebGLRenderTarget(resx, resy, pars);

    renderTargetVertical.texture.name = "UnrealBloomPass.v" + i;
    renderTargetVertical.texture.generateMipmaps = false;

    this.renderTargetsVertical.push(renderTargetVertical);

    resx = Math.round(resx / 2);

    resy = Math.round(resy / 2);

  }

  // luminosity high pass material

  if (LuminosityHighPassShader === undefined)
    console.error("UnrealBloomPass relies on LuminosityHighPassShader");

  var highPassShader = LuminosityHighPassShader;
  this.highPassUniforms = UniformsUtils.clone(highPassShader.uniforms);

  this.highPassUniforms["luminosityThreshold"].value = threshold;
  this.highPassUniforms["smoothWidth"].value = 0.01;

  this.materialHighPassFilter = new ShaderMaterial({
    uniforms: this.highPassUniforms,
    vertexShader: highPassShader.vertexShader,
    fragmentShader: highPassShader.fragmentShader,
    defines: {}
  });

  // Gaussian Blur Materials
  this.separableBlurMaterials = [];
  var kernelSizeArray = [3, 5, 7, 9, 11];
  var resx = Math.round(this.resolution.x / 2);
  var resy = Math.round(this.resolution.y / 2);

  for (var i = 0; i < this.nMips; i++) {

    this.separableBlurMaterials.push(this.getSeperableBlurMaterial(kernelSizeArray[i]));

    this.separableBlurMaterials[i].uniforms["texSize"].value = new Vector2(resx, resy);

    resx = Math.round(resx / 2);

    resy = Math.round(resy / 2);

  }

  // Composite material
  this.compositeMaterial = this.getCompositeMaterial(this.nMips);
  this.compositeMaterial.uniforms["blurTexture1"].value = this.renderTargetsVertical[0].texture;
  this.compositeMaterial.uniforms["blurTexture2"].value = this.renderTargetsVertical[1].texture;
  this.compositeMaterial.uniforms["blurTexture3"].value = this.renderTargetsVertical[2].texture;
  this.compositeMaterial.uniforms["blurTexture4"].value = this.renderTargetsVertical[3].texture;
  this.compositeMaterial.uniforms["blurTexture5"].value = this.renderTargetsVertical[4].texture;
  this.compositeMaterial.uniforms["bloomStrength"].value = strength;
  this.compositeMaterial.uniforms["bloomRadius"].value = 0.1;
  this.compositeMaterial.needsUpdate = true;

  var bloomFactors = [1.0, 0.8, 0.6, 0.4, 0.2];
  this.compositeMaterial.uniforms["bloomFactors"].value = bloomFactors;
  this.bloomTintColors = [new Vector3(1, 1, 1), new Vector3(1, 1, 1), new Vector3(1, 1, 1),
  new Vector3(1, 1, 1), new Vector3(1, 1, 1)];
  this.compositeMaterial.uniforms["bloomTintColors"].value = this.bloomTintColors;

  // copy material
  if (CopyShader === undefined) {

    console.error("UnrealBloomPass relies on CopyShader");

  }

  var copyShader = CopyShader;

  this.copyUniforms = UniformsUtils.clone(copyShader.uniforms);
  this.copyUniforms["opacity"].value = 1.0;

  this.materialCopy = new ShaderMaterial({
    uniforms: this.copyUniforms,
    vertexShader: copyShader.vertexShader,
    fragmentShader: copyShader.fragmentShader,
    blending: AdditiveBlending,
    depthTest: false,
    depthWrite: false,
    transparent: true
  });

  this.enabled = true;
  this.needsSwap = false;

  this.oldClearColor = new Color();
  this.oldClearAlpha = 1;

  this.basic = new MeshBasicMaterial();

  this.fsQuad = new Pass.FullScreenQuad(null);

};

UnrealBloomPass.prototype = Object.assign(Object.create(Pass.prototype), {

  constructor: UnrealBloomPass,

  dispose: function () {

    for (var i = 0; i < this.renderTargetsHorizontal.length; i++) {

      this.renderTargetsHorizontal[i].dispose();

    }

    for (var i = 0; i < this.renderTargetsVertical.length; i++) {

      this.renderTargetsVertical[i].dispose();

    }

    this.renderTargetBright.dispose();

  },

  setSize: function (width, height) {

    var resx = Math.round(width / 2);
    var resy = Math.round(height / 2);

    this.renderTargetBright.setSize(resx, resy);

    for (var i = 0; i < this.nMips; i++) {

      this.renderTargetsHorizontal[i].setSize(resx, resy);
      this.renderTargetsVertical[i].setSize(resx, resy);

      this.separableBlurMaterials[i].uniforms["texSize"].value = new Vector2(resx, resy);

      resx = Math.round(resx / 2);
      resy = Math.round(resy / 2);

    }

  },

  render: function (renderer, writeBuffer, readBuffer, deltaTime, maskActive) {

    this.oldClearColor.copy(renderer.getClearColor(new Color(0x000000)));
    this.oldClearAlpha = renderer.getClearAlpha();
    var oldAutoClear = renderer.autoClear;
    renderer.autoClear = false;

    renderer.setClearColor(this.clearColor, 0);

    if (maskActive) renderer.state.buffers.stencil.setTest(false);

    // Render input to screen

    if (this.renderToScreen) {

      this.fsQuad.material = this.basic;
      this.basic.map = readBuffer.texture;

      renderer.setRenderTarget(null);
      renderer.clear();
      this.fsQuad.render(renderer);

    }

    // 1. Extract Bright Areas

    this.highPassUniforms["tDiffuse"].value = readBuffer.texture;
    this.highPassUniforms["luminosityThreshold"].value = this.threshold;
    this.fsQuad.material = this.materialHighPassFilter;

    renderer.setRenderTarget(this.renderTargetBright);
    renderer.clear();
    this.fsQuad.render(renderer);

    // 2. Blur All the mips progressively

    var inputRenderTarget = this.renderTargetBright;

    for (var i = 0; i < this.nMips; i++) {

      this.fsQuad.material = this.separableBlurMaterials[i];

      this.separableBlurMaterials[i].uniforms["colorTexture"].value = inputRenderTarget.texture;
      this.separableBlurMaterials[i].uniforms["direction"].value = UnrealBloomPass.BlurDirectionX;
      renderer.setRenderTarget(this.renderTargetsHorizontal[i]);
      renderer.clear();
      this.fsQuad.render(renderer);

      this.separableBlurMaterials[i].uniforms["colorTexture"].value = this.renderTargetsHorizontal[i].texture;
      this.separableBlurMaterials[i].uniforms["direction"].value = UnrealBloomPass.BlurDirectionY;
      renderer.setRenderTarget(this.renderTargetsVertical[i]);
      renderer.clear();
      this.fsQuad.render(renderer);

      inputRenderTarget = this.renderTargetsVertical[i];

    }

    // Composite All the mips

    this.fsQuad.material = this.compositeMaterial;
    this.compositeMaterial.uniforms["bloomStrength"].value = this.strength;
    this.compositeMaterial.uniforms["bloomRadius"].value = this.radius;
    this.compositeMaterial.uniforms["bloomTintColors"].value = this.bloomTintColors;

    renderer.setRenderTarget(this.renderTargetsHorizontal[0]);
    renderer.clear();
    this.fsQuad.render(renderer);

    // Blend it additively over the input texture

    this.fsQuad.material = this.materialCopy;
    this.copyUniforms["tDiffuse"].value = this.renderTargetsHorizontal[0].texture;

    if (maskActive) renderer.state.buffers.stencil.setTest(true);

    if (this.renderToScreen) {

      renderer.setRenderTarget(null);
      this.fsQuad.render(renderer);

    } else {

      renderer.setRenderTarget(readBuffer);
      this.fsQuad.render(renderer);

    }

    // Restore renderer settings

    renderer.setClearColor(this.oldClearColor, this.oldClearAlpha);
    renderer.autoClear = oldAutoClear;

  },

  getSeperableBlurMaterial: function (kernelRadius) {

    return new ShaderMaterial({

      defines: {
        "KERNEL_RADIUS": kernelRadius,
        "SIGMA": kernelRadius
      },

      uniforms: {
        "colorTexture": { value: null },
        "texSize": { value: new Vector2(0.5, 0.5) },
        "direction": { value: new Vector2(0.5, 0.5) }
      },

      vertexShader:
        "varying vec2 vUv;\n\
				void main() {\n\
					vUv = uv;\n\
					gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n\
				}",

      fragmentShader:
        "#include <common>\
				varying vec2 vUv;\n\
				uniform sampler2D colorTexture;\n\
				uniform vec2 texSize;\
				uniform vec2 direction;\
				\
				float gaussianPdf(in float x, in float sigma) {\
					return 0.39894 * exp( -0.5 * x * x/( sigma * sigma))/sigma;\
				}\
				void main() {\n\
					vec2 invSize = 1.0 / texSize;\
					float fSigma = float(SIGMA);\
					float weightSum = gaussianPdf(0.0, fSigma);\
					float alphaSum = 0.0;\
					vec3 diffuseSum = texture2D( colorTexture, vUv).rgb * weightSum;\
					for( int i = 1; i < KERNEL_RADIUS; i ++ ) {\
						float x = float(i);\
						float w = gaussianPdf(x, fSigma);\
						vec2 uvOffset = direction * invSize * x;\
						vec4 sample1 = texture2D( colorTexture, vUv + uvOffset);\
						vec4 sample2 = texture2D( colorTexture, vUv - uvOffset);\
						diffuseSum += (sample1.rgb + sample2.rgb) * w;\
						alphaSum += (sample1.a + sample2.a) * w;\
						weightSum += 2.0 * w;\
					}\
					gl_FragColor = vec4(diffuseSum/weightSum, alphaSum/weightSum);\n\
				}"
    });

  },

  getCompositeMaterial: function (nMips) {

    return new ShaderMaterial({

      defines: {
        "NUM_MIPS": nMips
      },

      uniforms: {
        "blurTexture1": { value: null },
        "blurTexture2": { value: null },
        "blurTexture3": { value: null },
        "blurTexture4": { value: null },
        "blurTexture5": { value: null },
        "dirtTexture": { value: null },
        "bloomStrength": { value: 1.0 },
        "bloomFactors": { value: null },
        "bloomTintColors": { value: null },
        "bloomRadius": { value: 0.0 }
      },

      vertexShader:
        "varying vec2 vUv;\n\
				void main() {\n\
					vUv = uv;\n\
					gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n\
				}",

      fragmentShader:
        "varying vec2 vUv;\
				uniform sampler2D blurTexture1;\
				uniform sampler2D blurTexture2;\
				uniform sampler2D blurTexture3;\
				uniform sampler2D blurTexture4;\
				uniform sampler2D blurTexture5;\
				uniform sampler2D dirtTexture;\
				uniform float bloomStrength;\
				uniform float bloomRadius;\
				uniform float bloomFactors[NUM_MIPS];\
				uniform vec3 bloomTintColors[NUM_MIPS];\
				\
				float lerpBloomFactor(const in float factor) { \
					float mirrorFactor = 1.2 - factor;\
					return mix(factor, mirrorFactor, bloomRadius);\
				}\
				\
				void main() {\
					gl_FragColor = bloomStrength * ( lerpBloomFactor(bloomFactors[0]) * vec4(bloomTintColors[0], 1.0) * texture2D(blurTexture1, vUv) + \
													 lerpBloomFactor(bloomFactors[1]) * vec4(bloomTintColors[1], 1.0) * texture2D(blurTexture2, vUv) + \
													 lerpBloomFactor(bloomFactors[2]) * vec4(bloomTintColors[2], 1.0) * texture2D(blurTexture3, vUv) + \
													 lerpBloomFactor(bloomFactors[3]) * vec4(bloomTintColors[3], 1.0) * texture2D(blurTexture4, vUv) + \
													 lerpBloomFactor(bloomFactors[4]) * vec4(bloomTintColors[4], 1.0) * texture2D(blurTexture5, vUv) );\
				}"
    });

  }

});

UnrealBloomPass.BlurDirectionX = new Vector2(1.0, 0.0);
UnrealBloomPass.BlurDirectionY = new Vector2(0.0, 1.0);

export { UnrealBloomPass };
